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AD8067 Spice model vs data sheet

Question asked by jcx on Dec 12, 2012
Latest reply on Jan 8, 2013 by jcx

Playing with Audio DAC I/V op amp selection I tried Analog's AD8067 Spice model and found some problems when compared to the data sheet parameters, plots


the model's ~74 dB Avol doesn't come anywhere near the data sheet DC open loop gain of 100 dB min, 119dB typical


the .cir file comment shows the problem



the data sheet gain vs frequency plot doesn't show any such high frequency pole limiting DC gain, the table specs tell a different story too


one graph suggests +5 V single supply, 30 mA load could drag the gain down that far – but is that really the performance you want to build in to the default Spice model?



The output Z agrees well with the data sheet – everywhere it hardly matters, but the Spice model has a 60 MHz resonance with >2x the data sheet |Z|, drops to a flat R above 100 MHz – while the data sheet output Z plot keeps rising


its sorta useful to capture the Zout performance near the gain intercept frequency to see C load stability, peaking in the sim – even better to see the model be close for the next decade beyond



the AD8067.cir Vos of 1.5 mV is also annoying – according to the data sheet I can expect the factory to replace any AD8067 with such large Vos –  greater than the data sheet max Vos, way larger than the ~200-300 uV typical as verified by the Vos histogram in the data sheet

unless you're piling on worst case assumptions - say Vos tempco and high operating T  I don't see how such large Vos
belongs in the default Spice model



and I also like to point out that Ccm modeling parts do not connect to gnd in a real op amp – they are resolved with respect to the supply pins – how hard is it to make this better?

or even add reverse biased diodes with C voltage dependency from inputs to supply pins?